Tree harvesting method



g- 12, 1969 H. 0. BURKHALTER ET AL 3,460,288

TREE HARVEST ING METHOD 2 Sheets-Sheet 1 Filed April 25. 1967 SSNIGVBH8313M! BUI'LLSIOW inen mu Om" ON Om hmnEmuma 532 wwm. 0mm. ow 7 INVENTO5 R M n HE A% +f MU m T NS OE B W H.E HYU B N QM ATTORNEYS 1969 H. o.BURKHALTER EFAL 3,460,288

TREE HARVESTING METHOD Filed April 25, 1967 2 Sheets-Sheet 2 SSNICIVHHHELEN BUfllSIOW o o O Q N 8 v June May

! April MOISTURE METER READINGS Morch TIME-DAYS PERCENT WEIGHT LOSS BYWEIGHING 6O Jonu0ry--Februury S801 .LHSIBM :IO .LN3O 83d INVENTORQ N H.DON BURKHALTER ERNEST J. RUSSELL 5 & gb (WM bu Jim k ww oam, C

ATTORNEYS tlnited 3,460,283 TREE HARVESTING METHQD Harvey DonBurlrhaiter and Ernest J. Russet], Ruston, La.,

assignors to T. L. .Iames & fiornpany, Ind, Ruston, La.,

a corporation of Louisiana Filed Apr. 25, 1967, Ser. No. 633,536 int.Ci. AOf-lg 23/00; G011: 25/56, /02

US. C]. 4758 7 Claims ABSTRAUI OF THE DISCLOSURE A method of harvestingstanding trees wherein the tree is felled and is dried for an intervalof time while the crown is maintained intact on the stem. The optimuminterval of drying time is established by utilization of an electricmoisture meter to periodically indicate moisture content of the felledtree. When the moisture content of the felled tree ceases to be reduced,or starts to increase, as indicated by the meter, and in spite ofcontinued weight reduction of the tree, the need for completion ofharvesting is indicated if tree deterioration is to be circumvented.

FIELD OF THE INVENTION This invention relates to tree harvesting and,more specifically, to a commercial method of harvesting trees to achievea natural reduction of the moisture content of the wood product.

Heretofore it has been the practice in commercial tree harvesting, suchas in the production of pulp wood, poles, piling, or saw logs, to cut orfell a standing tree to be harvested and, at the same time, to removethe unmerchantable tree crown or limbs. Subsequent to felling andtopping, and to facilitate transportation to a mill, the severed,merchantable stem may be skidded to a staging area or bucked into milllengths. These harvesting steps are usually integrated and completed ina relatively short interval of time to enhance labor efiiciency and tocircumvented harmful tree deterioration or rot, which may make the woodproduct unmerchantable. In some operations, such as production of poles,piling or lumber, the woodp roduct is heated and dried at the mill inkilns to meet production standards as to moisture content.

Regardless of the use to which the wood product is to be put, these andother more sophisticated or mechanized methods of tree harvesting havethe common disadvantage that the wood product is transported to the millwhile it has a high moisture content, and is therefore unduly heavy andprone to deterioration.

It is an object of the present invention to provide a tree harvestingmethod which naturally reduces wood product moisture content and weight,and circumvents certain wood product deterioration.

In achieving this general object. the present invention provides a treeharvesting method wherein, after felling a standing tree, the tree crownis maintained intact on the tree stem for an interval of time determinedby moisture content and by deterioration considerations. In such acondition, the tree crown acts as a wick which sucks moisture from thestem, whereby not only is the drying the merchantable stem accelerated,but also the total naturally available drying effect is increased.

To understand the basis of the present invention, the anatomy and growthprocess of a tree should be considered. In the growth process of a tree,large amounts of water are drawn upwardly through the vascular system ofa tree from the soil, through its roots and stem, to the leaves of itscrown. Some of this water is required for growth of the tree, but amajor portion is passed off into 3,46%,288 ?atented Aug. 12, 1969 icethe atmosphere by the leaves through the process of transpiration. As isknown, this upward drawing movement of water from the roots to theleaves is caused by root pressure and, to a greater extent, by the pullexerted by water evaporation on the leaves. As early as 1840 Bouchen'edetermined that this drawing effect continued after a tree is severedfrom its stump and could be utilized to draw diverse liquids into thestem for various treatments. Accordingly, it has been theorized thatleaving a crown of a felled tree on the stem for an interval of timeafter felling might enhance the drying process of a stem to asignificant extent. In conducting field tests that resulted in thepresent invention, as will be discussed more fully hereinafter, it hasbeen found that if a crown is severed from the merchantable stemimmediately upon felling, as is the commercial practice, and if the stemis exposed to the atmosphere and permitted to dry for a period of time,the merchantable stem lost not more than about 6% of its weight.However, under identical conditions, if the crown is maintained intacton a stem of a felled tree and the severed tree is likewise permitted todry for the same period of time, weight reductions of as much as 30%have been achieved. Clearly the benefits afforded by such reduction ofweight are of major significance. Additionally, because the dryingprocess of the stem is accelerated, the threat of tree deterioration,which appears to be greater at higher moisture contents, is retarded.However, field tests that resutled in the present invention establishedthat both the maximum moisture content loss and weight reduction, aswell as the interval of time necessary for achieving the same, variesgreatly according to species and environmental conditions such as theseason of the year, precipitation, humidity, and movement, and others.In some instances, it has been found that one month is sutlicient toachieve the desired drying effect, while in other instances four monthsis necessary to fully achieve the benefits afforded by the presentinvention. Therefore, no standard or predictable drying period of timecould be accurately established. If the interval of drying time is tooshort, no substantial weight reductions are achieved. More problematicalis the fact that if the interval of drying time is too long, woodproduct deterioration may be encountered which results in making thewood product unmerchantable. These field tests establish that suchdeterioration commences after the tree has been dried for its optimumdrying period, progresses rapidly thereafter and may, in a short lengthof time after commencement of deterioration, make the wood productunmerchantable. Of particular significance is the fact that the fieldtests forming the basis of the present invention establish that thefelled tree continues to experience weight reductions as deteriorationprogresses. However, as will be more fully presented hereinafter, thesefield tests establish that prior to commencement of deterioration, themeasured moisture content of the filled tree ceases to reduce, and infact, peaks off and increases during the deterioration stage.

Thus, the present invention utilizes the basic transpiration process ofa tree to provide a method of harvesting standing trees wherein astanding tree is felled and the felled tree is dried for an interval oftime while the crown remains intact on the stem. Drying time isdetermined by periodically measuring the moisture content of the felledtree. According to the present invention, an electric moisture meter isutilized to periodically indicate the moisture content of the felledtree. At the time when the moisture content approaches its maximumreduction and fails to change, the need for severing the crown andfurther processing is indicated. It is particularly noteworthy that thepresent invention provides an indication of the need for completion ofthe tree harvesting process prior to the deterioration stage, in spiteof the fact that further weight loss may be experienced duringdeterioration.

3 BRIEF DESCRIPTION OF THE DRAWINGS In describing the invention,reference will be made to the accompanying drawings in which:

TABLE A Specie: Loblolly (entire tree), Tree No. Ali-1 Age, 14 years;D.I3.H., 7.2 Merchantable length, 32; crown length, 18

Weight loss Days since last Weight loss, elapsed since Weight weighingWeight loss percent, since Total weight Date weighed last weighing(pounds) (pounds) total (pounds) last weighing loss, percent Cut 491 7432 a 59 12 12 14 400 32 e1 7 17 21 35s 42 133 27 2a 340 18 151 5 30.735 335 5 s 1 31.77 42 335 156 31. 77

FIGURE 1 is a computerized graphic comparison of TABLE B moisture meterreadings of a test on loblolly pine and the s L b1 u t m Tr A34 averageweight losses of six such trees harvested in ac- 0 o y (Hm cordance withthe present invention; and rg p Weight loss h, 21 t that sincelastWeight total Total weight FIGURE 2 13 a p 1c coqipanson 51ml r Dateweighed weighing (pounds) (pounds) loss, percent shown in FIGURE 1 butshowing such test results for out 530 slash pine. is 525 5 "f5; 13 52010 1. 88 DETAILED DESCRIPTION OF THE INVENTION it a 2,4 5 2.8 Thepresent method of harvesting trees ut1l1zes the 17 June 2% g principleof transpiration and the physiological growth TABLE 0 Specie: Slash(entire tree), Tree No. 134-2 Age, 19 years; D.B.H., 7.4 Merehantablelength, 38; crown length, 20'

Weight loss Days since last Weight loss, elapsed since Weight weighingWeight loss percent, since Total weight Date weighed last weighing(pounds) (pounds) total (pounds) last weighing loss, percent (a July Cut483 3 u y 7 430 53 53 10. 97 10. 97 20 July 14 402 28 81 6. 5 16. 77 27July 21 356 46 127 11. 44. 26. 2e 3 August 28 340 14 141 a. 93 2e. 19

process of trees to naturally reduce the moisture content TABLE D andweight of a tree after felling. Such is accomplished specie, Slash (Stemonly), Tree p by mamtammg the tree crown intact on the tree stem afterDays elapsed Weight loss felling and exposing the entire tree toatmosphere for an 4? 4 since last Weight total Total weight. extendedinterval of time Prior to further processmg 0 Date weighed weighing(pounds) (pounds) loss, percent As has heretofore been discussed, in thetree grow h Cut 585 process water is drawn from the soil, through theroots and 1 2% stem, to the tree crown. This drawing action 1sgenerated, 21 570 15 r, 3 August 28 567 18 3 to a large extent, by waterevaporation from the leaves of the crown as such water is passed offinto the atmosphere through the process of transpiration. If a tree issevered from its roots and stump, a portion of the growth processcontinues for a period of time. However, since the supply of .waterafforded by the soil and roots is cut off, the leaves of the crown canonly draw that water remaining in the stern. Thus, the desired dryingaction of the merchantable stem of the tree is provided.

That this transpiration drying action forming the basis of the presentinvention accelerates and extends wood product drying has been verifiedby extensive field tests on softwoods (Conifers) and hardwoods by thepresent inventors. Such field tests were conducted in all seasons of theyear for loblolly pine (Pinus taeda) and slash pine (Firms elliotti). Inconducting these field tests, a large number of trees were cut and eachentire tree, with its crown intact, was weighed immediately aftertelling by utilization of Fairbanks beam-type scales to establish greenweight of the individual tree. These trees were exposed to theatmosphere and reweighed at regular intervals to measure weight loss.

To verify that tree drying was accelerated by maintaining the crownintact during the drying period, similar trees of the same species werefelled at the same time and the merchantable stem severed from thecrown. Each mer- Many such tests were conducted but typical are theresults of such tests on a pair of comparable loblolly pines, (treenumbers A3-1 and A3-4) as presented in Tables A and B, wherein weightlosses for the entire tree, (unsevered crown) and stem alone (severedcrown), respectively, are recorded. Tables C and D indicate the resultsof similar tests on a pair of comparable slash pines (tree numbers 1B4-2and B4-4). As will be apparent from an inspection of Table A, treenumber A3-l, which was dried for approximately one and one-half monthswith its crown intact, lost over 31% of its weight during the dryingperiod. Tree number A3-4 of Table B from which the crown was severedfrom the stem immediately after felling experienced a mere 2.8% weightreduction in a like period of time. Similarly, as presented in Tables Cand D, slash pine number B4-2, which was dried with its crown intact fora period of less than one month, experienced better than a 29% weightreduction as opposed to a 3% weight reduction of slash pine number B4-4,which was dried for the same interval of time with the crown severedfrom the stem.

Of the various field tests conducted on softwoods dried with the crownsintact, weight losses as high as 35% were achieved as opposed to weightlosses of an average of around 3% for trees dried with the merchantableportion severed from the crown. Similar tests were conducted during thegrowth season for hardwoods, such as red oak (Quercus falcata Michx),white oak (Quercus alba L), sweetgum (Liquidambar styraciflua L.),blackgum (Nyssa sylvatica Marsh), and hickory (Carya tomentosa Nutt).The results of these tests indicate that hardwoods dried with the crownsintact experienced weight losses as high as 28% as opposed to weightlosses for drying the merchanta ble portion alone of a maximum of 8.8%.

To compare the effect of drying in both the severed and unserveredconditions of the crown on weight loss of the merchantable portionsalone, cord weight tests were conducted. Green and dried weights of astandard cord of 128 cubic feet were measured. These tests wereconducted by felling a quantity of similar trees at the same time.Periodically, a number of trees of this group were topped, bucked andcord weight measured. The tree crowns were maintained intact during thedrying period. In conducting these tests, volume determinations in cordswere made in accordance with pulpwood industry practice, and the woodproduct was delivered and sold to a pulp mill. Net weights weredetermined by weighing a truck utilized for transporting to the .pulpmill in both empty and loaded conditions by utilizing a portableLoadmaster type A scale similar to those used in checking truck weightsby law enforcement agencies. The results of the cord weight tests onloblolly pine and slash pine are typified by the results presented inTable E and F below:

TABLE E Specie: Loblolly (dried with crown), Test phase No. 3A

Days Number of Weight elapsed cords Weight loss per Total Date sincelast weighed per cord cord weight loss, weighed weighing (cords)(pounds) (pounds) percent 5 May Cut 11.82 4, 996 4 June 1 30 6.15 4,166830 16. 61 8 June 34 6. 35 4, 063 933 18. 97

TABLE F Specie: Slash (dried with crown), Test phase No. 4B

Days Number of Weight elapsed cords Weight loss per Total Date sincelast weighed per cord cord weight loss, weighed weighing (cords)(pounds) (pounds) percent 6 July- Cut 11.38 5,138 20 July- 14 6.25 4,312826 16.07 21 July... 15 6.45 4,226 912 17. 75

As will be apparent from a review of Table E, a cord of loblolly driedwith its crown intact for a relatively short period of approximately onemonth experienced nearly 19% weight loss. Similarly, as presented inTable F, a cord of slash dried for a like period of time with its crownintact experienced a weight loss of approximately 18%.

It should be noted that the many field tests conducted indicate that theinterval of drying required to achieve an optimum weight reductionvaries greatly for a particular specie from season to season.Environmental conditions such as precipitation, humidity, wind movement,and the like which normally affect the growth process of a tree likewiseaffect drying time requirements. In some instances, as during warm, dry,summer periods, a drying time of approximately one month is adequate toachieve optimum weight loss. However, in other instances, as duringwinter months or slow tree growth periods, more than four months isrequired. In commercial practice it is necessary that optimum dryingtimes be conveniently and reliably identified for efficiency reasons.But further, it is of the utmost importance that the harvesting processbe completed prior to wood product deterioration or rot caused by fungi.Such deterioration, once commenced, progresses rapidly, particularly inthe summer months and may, within a period of a few weeks, render a treeunmerchantable as the wood becomes soft or spongy. In this light, adrying period in which an entire felled tree is exposed to theatmosphere must be cut short prior to the deterioration stage and theharvesting process completed shortly thereafter. This problem iscomplicated by the following considerations: First, identification ofthe existence of such deterioration requires disection and inspection ofa tree by a highly skilled technician. Further, it has been establishedin other field tests to be discussed hereinafter, that trees dried withthe crown intact continue to experience weight reductions through thedeterioration stage. Therefore, weight loss alone is not a reliableindication of the optimum time to complete harvesting to circumventdeterioration. However, it has also been established that prior todeterioration, moisture content of the wood product, as measured in amanner hereinafter discussed, ceases to reduce, and starts to increase.Therefore, by utilization of this concept, optimum drying time may beidentified and deterioration circumvented.

To accurately identify the optimum drying time for felled trees driedwith their crown intact, the present invention includes utilization of abattery-powered, handoperated electric moisture meter, such as theLaucks Sentry, which indicates the resistance to a flow of electricitythrough a subject composition. Electrical resistance varies inaccordance with moisture content. Such meters include a conductivecontact surface adapted to abut the outer periphery of a tree. Uponactuation, electricity is directed from a battery to the contact surfaceand composition, and a gage is provided which is calibrated to indicateresistance to a flow of electricity of the composition.

TABLE G Specie: Loblolly (entire tree), Tree No. AM I Merchantablelength, 31; D.B.H., 8.2 Crown length, 24

Days Weight loss Weight Weight loss, Total elapsed since last losspercent, weight Moisture Date since last Weight weighing total sincelast loss, meter weighed weighing (pounds) (pounds) (pounds) weighingpercent reading Dec. 2 Cut 510 25 Dec. 9 7 489 21 4. 11 23 Dec. 17 15492 3 3. 52 25 Dec. 2.. 20 481 11 5. 68 26 Dec. 30 28 474 7 7. 05 29Jan. 10 39 465 9 8.82 14 Jan. 17 46 457 8 10.39 10 Jan. 31 455 2 10. 7814 Feb. 7- 67 442 13 13.33 7 Feb. 21--- 81 427 15 16.27 6 Mar. 8 96 41017 19. 60 5 Mar. 397 13 3. 17 22. 15 5 Mar 112 374 23 136 5. 79 26. G6 4Mar. 119 355 19 5.08 30. 39 4 Apr. 126 342 13 168 3. 66 32. 94 3 Apr.147 33 7 2.04 34. 31 5 May 6 155 334 1 176 .23 34. 50 6 May 20 169 326 8184 2. 39 36.07 5 May 30- 179 310 16 200 4. 90 39. 21 5 June 6 186 29416 216 5. 16 42. 35 3 TABLE II No. BM-l Days Weight loss Weight Weightloss, Total elapsed since last loss percent, weight Moisture Date sincelast Weight weighing total since last los motor weighed weighing(pounds) (pounds) (pounds) weighing percent; reading Dec. 2 Gilt 432Dcc.9 7 411 21 221 4.86 4.86 26 409 2 23 486 5. 32 22 401 8 31 1. 95 7.17 20 28 393 8 3'.) 1. ill) 9. 02 17 3!) 384 J 48 2. 29 11. ll 13 46 374ll) 58 2. 60 13. 42 12 60 373 1 59 26 13. 65 1 67 363 ll) 69 2. 68 15. 914 81 355 8 77 2. 20 17. 82 13 96 341 14 91 3. 94 21. 06 J 105 335 697 1. 75 22. 45 9 112 323 12- 109 3. 58 25. 23 6 119 315 8 117 2.4727.08 6 126 305 10 127 3. 17 29. 39 5 147 296 9 136 2. 95 31. 48 J 155296 0 136 31. 48 10 169 293 3 139 1. 01 32. 17 U 179 286 7 146 2. 38 33.79 7 186 280 6 152 2. 09 35. 18 4 In conducting these tests, a number ofloblolly and slash pines were felled and exposed to the atmosphere foran extended period of time with their crowns intact. A Fairbanksbeam-type scale was utilized to establish the green weight of the entiretree upon felling and to reweigh the entire tree at regular intervalssimilar to the method discussed in regard to Table A. At eachreweighing, the moisture content of each tree was measured byutilization of a moisture meter. Typical of such tests are the resultspresented in Table G wherein weight losses and moisture meter readingsfor loblolly tree number AM-l, dried with its crown intact, arepresented, as well as in Table H wherein similar information ispresented for slash tree number BM-l.

At the time of felling the test trees, like trees were felled to serveas deterioration indicators. Individual trees of this latter group weredissected and inspected periodically during the drying period of thetest trees to assure that the deterioration stage of the group cuttinghad not been reached. Deterioration was identified by visual observationand by penetration and cutting tests. In conducting such tests, a sharpknife wa forced into various sections of the trees being tested, and theresistance to blade penetration was measured to determine whethercutting tests on an indicator tree should be made. Periodicallythroughout the tests or if the test tree appeared to be soft or spongy,the indicator trees were cut into sections while measuring resistance tocutting. Subsequent to cutting, cross sections of the indicator treeswere visually inspected for evidence of deterioration. It is well knownthat deterioration occurs more quickly in those periods of the year whenthe tree growth process is accelerated. Advantageously, tree drying,according to the present invention, is also accelerated at these times.

As will be apparent from a review of Tables G and H, in a period ofapproximately four months, a minimum meter reading and a percentageweight loss of approximately 33% for loblolly and approximately 29% forslash were achieved. Subsequently, the recorded moisture meter readingcommenced to peak-off and increase in spite of the fact that furtherweight losses were experienced. Such was the pattern in all treestested. It has been established that deterioration of the test treescommenced at least one week after the moisture meter readings started toincrease. All of the trees tested continued to lose weight throughoutthe deterioration stage and at the conclusion of the test period none ofthe trees was merchantable because of deterioration.

In all trees tested, such a peak-off of moisture meter readings prior tothe deterioration stage was noted, in spite of the fact that furtherweight loss was experienced. it is theorized that an increase inmoisture meter readings, coincident with a decrease in weight of theoverall tree, results from the fact that in measuring moisture content,the moisture meter contacts the outer periphery of a test tree. Itappear that just prior to deterioration, the outer periphery of a treetakes on moisture, as reflected by increased meter readings, while theinner portion of the tree continues to dry and becomes lighter as thecrown continues to draw moisture therefrom.

In this light, utilization of a moisture meter to determine optimumdrying time is not only beneficial because it conveniently indicates theextent of moisture loss experienced in the drying process, but alsobecause it indicates the maximum drying period short of the criticallimits established by deterioration. It is particularly noteworthy thatthe peak-off stage of moisture meter readings occurs a reasonable timebefore measurable deterioration commences, and therefore provides acushion or grace period in which harvesting may be completed.

Referring to FIGURE 1, a graphic comparison of moisture meter readingsfor loblolly tree number AM-l and average weight losses for a compositeof six loblolly test trees (numbers AM-l-6) is presented. In eachinstance, a computer and recognized computer techniques were utilized toestablish by quadratic regression analysis a smooth curve of the fieldtest results based on computed standard deviation over exactly equalintervals of time. A similar graphic comparison for slash tree numberBM-l and composites BM-1-6 is presented in FIG- URE 2. The correlationbetween moisture meter readings and weight loss during the optimumdrying time is noteworthy.

The results of these field tests and analysis indicate that loblolly andslash pines in the test area in Louisiana should be dried with the crownintact until a weight reduction of the entire tree of from 28-35 isexperienced. However, because the drying time to achieve such a weightreduction varies greatly dependent on ambient conditions, and becauseweight loss tests may not be feasible in a commercial operation,utilization of a moisture meter to determine weight loss affords a morereliable or convenient alternative. But still further, the advantagesafforded by utilization of a moisture meter in practicing the presentmethod of harvesting are magnified by the consideration that thepeak-off stage of moisture meter readings provides a warning in advanceof deterioration that the harvesting process should be completed.

By utilization of the present method of harvesting trees, it iscommercially practical to accurately identify an optimum drying time fora group cutting by periodically measuring the moisture content of asingle sample tree. Regardless of the calibration of a moisture meter,the pattern of moisture content reductions establishes critical limitsshort of deterioration. In spite of the fact that drying rates and'totalamounts might vary widely from area to area, specie to specie, and aredependent upon environmental conditions, the advantages afforded by thepresent invention are conveniently available.

In describing the present method of harvesting trees, reference has beenmade to but a single preferred embodiment of the present invention. Itshould be appreciated by one skilled in the art that various additions,deletions and modifications may be made which fall within the scope ofthe present invention which i to be ascertained by the following claims:

1. A method of harvesting standing trees comprising:

felling a standing tree;

exposing the felled tree with its crown intact to the atmosphere for aninterval of time established by ascertaining the approximate moisturecontent reduction of the felled tree; and

severing the tree crown prior to deterioration of the merchantableportion of the tree, the time of said severing being based upon thepreviously ascertained moisture content reduction.

2. A method of harvesting standing trees according to claim 1 whereinthe moisture content reduction of the felled tree is established bymeasuring the resistance to flow of electricity through the tree.

3. A method of harvesting standing trees according to claim 2 whereinresistance to flow of electricity is periodically measured and whereinthe crown is severed shortly after the resistance ceases to diminish,before the resistance substantially increases but while the treecontinues to experience a reduction in weight.

4. A method of harvesting standing trees according to claim 2 wherein agroup of trees are substantially concurrently felled and the moisturecontent reduction thereof is ascertained by measuring the moisturecontent of only certain of the trees.

5. A method of harvesting standing conifers comprising:

felling a standing conifer;

exposing the felled conifer with its crown intact to the atmosphere foran interval of time established by ascertaining the approximate moisturecontent reduction of the felled conifer and for an interval of timerequired to achieve at least a 28 percent weight loss of the conifer;and

severing the crown prior to deterioration of the merchantable portion ofthe conifer, the time of said severing being based upon the previouslyascertained moisture content reduction.

6. A method of harvesting standing conifers according to claim 5 furtherincluding testing the trees resistance to penetration prior to severingthe crown.

7. A method of harvesting conifiers during the Winter and summer months,said method comprising:

felling a first group of conifers during the winter months;

felling a second group of conifers during the summer months; exposing tothe atmosphere the conifers of the first group, each with its crownintact, for a first interval of time established by ascertaining theapproximate moisture content reduction of at least certain of the firstgroup; exposing to the atmosphere the conifers of the second group, eachwith its crown intact, for a second interval of time established byascertaining the approximate moisture content reduction of at leastcertain of the second group, said second interval of time beingsubstantially shorter than said first interval; and

severing the crowns prior to deterioration of the merchantable portionof the conifers, the times of said severing being based upon thepreviously ascertained moisture content reductions.

FOREIGN PATENTS 904,639 2/1954 Germany.

ROBERT E. BAGWILL, Primary Examiner US. Cl. X.R.

